                1. Field of the Invention        
The present invention relates to a touch control apparatus and a touch control method that can be applied to an electronic instrument. More particularly, the present invention relates to a technique for obtaining a touch response optimal for a keying power of a user.
2. Description of the Related Art
Typically, a characteristic of the touch response in an electronic keyboard instrument, such as an electronic piano, is determined in accordance with a touch curve. The keyboard instrument, which can control the touch response, has in each key a first key switch S1 to be turned on by a first push depth and a second key switch S2 to be turned on by a second push depth deeper than the first push depth. Signals indicating an on state and an off state of the first key switch S1 and the second key switch S2 are supplied to a touch sensor. The touch sensor measures a time until the signal indicating that the second key switch S2 is turned on is inputted after the signal indicating that the first key switch S1 is turned on is inputted, and thereby detects a key push speed Δt (=S2−S1). As shown in FIG. 1, this key push speed Δt is converted into 128-stage digital data, and outputted as touch data.
The touch data outputted from this touch sensor is further converted in accordance with any of touch curves T1 to T3 shown in FIG. 2. Thus, a velocity value to be used for producing a tone is obtained. A user can select any one of the touch curves T1 to T3 to be used (this is referred to as “a function of selecting a touch curve”). By the way, the touch curve T1 is referred to as “Normal”, and it is designed such that a sound, which is the nearest an acoustic piano, is generated when a person having a standard keying power operates a keyboard. The touch curve T2 is referred to as “Light”, and it is used to obtain a large velocity value with a weak touch. This touch curve T2 is suitable for a person having a weaker keying power than a standard keying power, such as a low age group or a high age group. Also, the touch curve T3 is referred to as “Heavy”, and it is used to obtain a small velocity value with a strong touch. This touch curve T3 is suitable for a person having a stronger keying power than the standard keying power.
Since a maker usually provides the touch curves T1 to T3, the user can not change them arbitrarily. Hence, a touch control apparatus that can attain a touch response coincident with a taste of the user is desired. Especially, even the person having a relatively weak keying power, such as the low age group and the high age group, has recently desired the play of a high level in which the strong and weak keying powers are used. This results in a problem that only the conventional function of selecting the touch curve can not correspond to a wider age group.
In order to solve above-mentioned problem, Japanese Laid Open Patent Application (JP-A-Showa, 60-68385) discloses “TOUCH RESPONSE APPARATUS” (hereafter, referred to as a first prior art). This touch response apparatus is designed such that a velocity value is entered manually for each of 32 kinds of push key velocities to thereby prepare touch curves and store in a memory. Then, at a time of a play, a velocity value corresponding to a key push speed is read out from the memory, and it is accordingly reflected in the play.
Also, Japanese Laid Open Patent Application (JPA-Heisei, 11-38975) discloses “APPARATUS FOR SETTING VELOCITY CURVE IN ELECTRONIC KEYBOARD INSTRUMENT” (hereafter, referred to as a second prior art). In this apparatus, the velocity values at the times of the weakest keying power and the strongest keying power are entered to thereby generate a velocity curve
Moreover, Japanese Patent No. 2896948 discloses “APPARATUS FOR SETTING TOUCH RESPONSE FOR KEYBOARD” (hereafter, referred to as a third prior art). In this apparatus, each of a weak hit, a middle hit and a strong hit is performed a plurality of times to accordingly calculate the average of the velocity t, values for each hit. Then, they are linearly interpolated to thereby obtain a touch curve.
However, in the touch response apparatus according to the first prior art, many manual operations are required to prepare the touch curve. Thus, it takes a long time to obtain the desirable touch curve. Also, high music knowledge and experience are required to prepare the touch curve capable of obtaining the desirable touch response. This results in a problem that it is difficult to prepare the touch curve for a beginner.
In the apparatus according to the second prior art, it is necessary to enter the velocity values at the times of the weakest keying power and the strongest keying power. Thus, it takes a long time to prepare the touch curves. Also, the above-mentioned Japanese Patent No.2896948 does not disclose an input portion of the weakest value and an input portion of the strongest value in detail. However, from the descriptions in which the velocity value at the time of the weakest keying power is set to “10” (20 to 21 lines of a fourth column) and the velocity value at the time of the strongest keying power is set to “140” (30 to 31 lines of the fourth column), it may be understood that the input of the velocity value is done from an input device other than the keyboard device. Thus, since the input device is required, the configuration of the electronic instrument having the apparatus for setting a touch curve is complex and its cost is expensive.
In the apparatus according to the third prior art, it is necessary to enter the velocity values at the times of the weak hitting, the middle hitting and the strongest hitting. Thus, it takes a long time to prepare the touch curve. Moreover, at a time of the play, only the touch response based on the prepared touch curve is reproduced, which does not imply that the play of a user having a weak keying power can be simulated as if it is a play of a user having a standard keying power.
Moreover, the second and third prior arts require the touch data in the case of the keying powers through the different forces such as the weak, middle and strong keying powers. However, it is difficult that the beginners know what degree of keying power leads to the weak hitting, the middle hitting or the strong hitting. Thus, it is difficult to obtain the desirable touch curve.
Moreover, Japenese Laid Open Patent Application (JP-A-Heisei, 4-60590) discloses “ELECTRONIC MUSICAL INSTRUMENT”. In this electronic musical instrument, touch data is automatically changed such that player can play by the desirable key touch.
Furthermore, Japanese Laid Open Patent Application (JP-A-Heisei, 6-167971) discloses “PERFORMANCE EQUIPMENT”. This performance equipment, when the player plays a predetermined number note, calculates an average of the velocity, then automatically chooses a velocity change characteristic that is the optimal for a performance characteristic of the player based on this calculation result.